Rotary pump.



H. T. HERRING.

ROTARY PUMP.

APPLIQATIOI mum 101124, 1912.

1,066,815, Patented July 8, 1913.

Mfhesses. .lr n anlor. v

HERBERT THOMAS HERRING, OF LONDON, ENGLAND.

ROTARY PUMP.

Specification of Letters Patent.

Patented July 8, 1913.

Application filed June 4, 1912. SerialL-No. 701,477.

To all whom it may concern Be it known that I, l-lnnunair Tno'uas I'IERRING, a sub]ect of theKing of Great Britain, residing at London, England, have. invented new and useful Improvements in Rotary Punips,-of which the following is a specification, i f

This invention relates to improvements in rotary pumps of the kind in ivhich a pairof toothed pistons are geared together within a suitably shaped casing, the rotation of the said pistons etl'ecting theexhaustion, compression, or circulation of air, gas, or other fluid.

'In the specifications of English patents granted to me dated the 13th May, 1908, and

the 23rd September, 1909, and numbered 10,404: and 21,729 respectively, and in the specification of a German patent granted to.

me No; 224,7 69, I have described certain def vices for retaining in pumps of the above mentioned kind, especially when used for exhaustin r or com )ressin air or "as sufhcient lubricating liquid to keep, on the one hand, the teeth or leaves. of the pistons pro icrly lubricated, and, on the other hand, sullicient liquid to keep the said teeth or leaves sealed,

so as to prevent an or gas passing back through the pump, thereby enabling the latter to exhaust andcompress air or gas more effectively than hereto-fore, and at same time to enable the pump to be started without having to charge or prime it by hand or by special devices.

In the aforesaid specification No. 10,-t04; the means employed for these purposes consist of a by-pass pipe external to the pump; and in the aforesaid specifications Nos. 21,799 and 224,769 some of the means consist of grooves or channels formed in the interior of the casing or of its covers. It is through this by-pass pipe, or through' these grooves or channels, as the case may be, that the pum'p,when in motion, maintains a constant circulation of a small portion of the said liquid from the compression or positive side of the pump to the suction or negative'side thereof, a valve or other suitable device be "ing provided for the purpose of regulatinto any required number of. the cells or spaces between the teeth or .leavcs ot the pistons atter the said teeth or leaves have swept past the inlet port, and have come into more or less close contact with the inner surface of the pump casing.

The liquid traversing the bypasses comes in contact with the points, of the advancing leaves elt'ectuallysealing the said points and preventingthe air or gas, already in the cells, from escaping baclnvard toward the suction chamber. The jets of liquid issuing from the by-passes into the cells or spaces displace very little of the airior gas therefrom, but rather tend to compress such air or gas. And. in order that my said-invention may be fully understood, I will proceed to describe the same with the aid of the accolnpanying drawings, in which Figure 1. is a vertical section of a pump of the kind in question with mypermit inven tion applied thereto; and Fig. 2 is a section taken on the line A -A of Fig. 1.

a represents the body or casing of the pump, Z), Z) the toothed pistons rotating in gear with each other in the said casing in the manner well understood in connection with this class of pump.

' c is the outlet or delivery port from the pump casing, and, (Z is the inlet or suction port leading thereto.

0 is the delivery or positive pressurechamber corresponding to the chamber marked 0 in the aforesaid English specification No. 10,40 of 1908, and in the German specification No. 2%,769, and containing a supply of suitable lubricating liquid f.

is the suction or negative pressure chamber chamber corrcspmiding to the marked Z) in the aforesaid English and 'Ger' man specifications.

Z is the delivery pipe from the piston pressure chamber 0, and m is the inlet pipe to the suction or negative pressure chainbcr y As above described theliquid traversing the 'by-passes It comes in contact with the points of the advancing teeth or leaves, et-.

fectually sealing the said points, and pre- .-vent1ng the air or gas already in the cells 71 .from escaplng backward toward the suction port" (Z andchamber 9;.

The by-pass'es h are formed in the end cover of the pump and start from a recess 12 formed therein, as shown, with its lower edge placed at adistance equal to half the thickness of the base of a tooth or leaf,

above the center line B B joining the axis" of the two pistons Z b-, just-where the teeth of one piston. enter thecells or spaces of. the other piston alternately, and where considerable power has to be exerted in ordinary pumps; not fitted with this arrangement, to force the'quantity ofliquich shown by darkshading, through the'very narrow clearance space 72 into the pressure cham her e 01 through the toy-passes h to the'cells.

By this arrangement that quantity of liquid, or some of it,.passes by the by-passes h intothefront or first cells i endwis'e thereof,

and at the same time causes a reduction of the power required to drive the pump. Preterably the recess 91 extends laterally in both directions from 'the center to the curved surfaces of the bodies of the pistons b from which the teethor leaves spring; and the upper edge of the recess it may be at a distance above the lower edge equal to ab'out; thedist-ance apart of twoadjacent teeth or leaves at the rootthereof, as shown in Fig. l.

The bypasses hin the end covers may consist merely offgrooves cut. in theface I of the cover fr0m 'the;recess n to the inner always into the front or first cells.

curved surface of the casingias shown in Fig. 1,'or they may be made as passages q in the thickness of the cover, as shown in the section. Fig. 2,"With a short passage [1, at the outer end leading to the floor of the cells 1'. y Y

The delivery of the liquid from between the teeth or leaves into the recess n and thence to the cells below takes place altersaid outlet opening, a suction chamber communicating with'sa'id inlet opening, and liquid conveying passages formed in said end cover, said passages communicating with the space between the interm'eshing teeth. and ,with the spaces between adjacent teeth. and thecasing on opposite sides of said inlet opening.

In testnnon whereof I have 'si 'ned mv .Y. a

name to this specification in the presence of two subscribing ivit-nesse HERBERT THOlV S HERRING. Witnesses: STEPHEN EDWARD GUNYON, I. J. WORTH. 

